|Publication number||US7497008 B2|
|Application number||US 11/211,877|
|Publication date||Mar 3, 2009|
|Filing date||Aug 24, 2005|
|Priority date||Aug 24, 2005|
|Also published as||CN1920956A, CN1920956B, US20070048624|
|Publication number||11211877, 211877, US 7497008 B2, US 7497008B2, US-B2-7497008, US7497008 B2, US7497008B2|
|Inventors||Tsung Yuan Chen, Frederick Hayes Dill, James Mac Freitag, Kuok San Ho, Wipul Pemsiri Jayasekara, Kim Y. Lee, Mustafa Michael Pinarbasi, Ching Hwa Tsang, Patrick Rush Webb|
|Original Assignee||Hitachi Global Storage Technologies Netherlands B.V.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Classifications (29), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention relates to thin film magnetic transducers for sensing magnetic fields in magnetic recording media and more particularly to magnetic transducers used in magnetic disk drives.
A typical prior art head and disk system 10 is illustrated in block form in
In a disk drive using perpendicular recording the recording head is designed to direct magnetic flux through the recording layer in a direction which is generally perpendicular to the plane of the disk. Typically the disk for perpendicular recording has a hard magnetic recording layer and a magnetically soft underlayer. During recording operations using a single-pole type head, magnetic flux is directed from the main pole of the recording head perpendicularly through the hard magnetic recording layer, then into the plane of the soft underlayer and back to the return pole in the recording head. The shape and size of the main pole and any shields are the primary factors in determining the track width.
Perpendicular magnetic recording is considered to be superior to longitudinal magnetic recording for ultra-high density magnetic recording. The increase demand for higher areal density has correspondingly led to increase demand to explore ways to reduce the width of the write pole piece, increase the write field strength, and improve the write field gradient. Experimental evidence and modeling have shown that a trailing shield single pole writer (SPT) design achieves a 4-5 dB media signal to noise advantage over writing with the trailing edge of an unshielded pole, increase in dHy/dx of the head field, reduce partial erasure, and improve saturation. These features improve transition sharpness (linear resolution) and permit higher coercive field media (improved stability).
Lead overlay designs for read sensors provide an advantage in improved stability and amplitude. The primary problem is the wide MRW. In this design, track width controlled by the separation of the electrically conductive leads on top of the sensor is smaller than the full width of the sensor. The lead overlay design moves the track edges away from the active sensor region. A prior art spin valve head 12A with overlaid leads is illustrated in
In published U.S. patent application 20040257713 by Pinarbasi, et al., Dec. 23, 2004, a lead overlay magnetoresistive sensor is described with leads having substantially vertical end walls to accentuate sense current near the ends of the leads. Insulating layers isolate the hard bias layers from the path of the sense current. After a first photoresist liftoff structure has been removed, a second layer of photoresist is formed and patterned. The second layer of photoresist does not have the usual undercut liftoff structure. Instead, the second layer of photoresist has substantially vertical walls. Lead material may be conveniently chosen from low resistance, substantially inert conductors such as rhodium, gold, ruthenium, and the like.
In published U.S. patent application 20030011943 by Webb, et al., Jan. 16, 2003, various embodiments of spin valve sensors with overlaid leads are described. A first embodiment for a bottom spin valve deposits a cap layer over the sensor then “notches” to expose the outer edges of the sensor. The overlaid leads are deposited in contact with the exposed side of the sensors. A second embodiment “notches” down through the free layer, as well as, the cap then refills with copper and NiFe before depositing the overlaid leads. A third embodiment “notches” down through the free layer and partially into the spacer and refills with NiFe before depositing the overlaid leads. A fourth embodiment “notches” down through the free layer and completely through the spacer and refills with NiFe before depositing the overlaid leads. A top spin valve embodiment notches through the cap, AFM layer and optionally into or through the pinned layer before forming the leads that contact the pinned layer.
In published U.S. patent application 20050007706 by Dovek, et al., Jan. 13, 2005 describes a design in which an additional antiferromagnetic layer is added under the overlaid leads in a bottom spin valve design. The extra antiferromagnetic layer extends over the hard-bias pads onto the top of the spin valve and is coterminous with the lead material. The longitudinal bias provided by the hard-bias pads extends, it is said, without attenuation right up to the edges of the leads, so that the physical and magnetic widths of the sensor are essentially identical.
An embodiment of the invention is a read head which can be used in a disk drive, and a method of fabricating the read head, with overlaid lead pads that contact the top surface of the sensor between the hardbias structures to define the electrically active region of the sensor. The hardbias structures are electrically insulated from direct contact with the sides of the sensor by a layer of insulating material. The contact area on the top of the sensor is minimized by sidewall deposition of a conductive material to form leads pads on a photoresist prior to formation of the remainder of the leads. By using sidewall deposition to form the lead pads, the contact area on the sensor is minimized which is an advantage of the invention. The layers for the sensor preferably include a cap of ruthenium. Ruthenium oxide is conductive, so it provides conductivity, as well as, corrosion protection. To fabricate the head the back edge of the sensor is milled first, then an insulating layer is deposited to insulate the back edge from contact with the leads. After a CMP, a photoresist pad is patterned over the area of the sensor to define the hardbias structures. The sensor stack is partially milled through (notched) to expose the sides of selected layers where the hardbias structures will be formed. A thin insulating layer is deposited to electrically insulate the sides of the sensor, then the hardbias structures are formed. A CMP is used to liftoff the resists for the hardbias structures. A photoresist for the leads is formed over the center of the sensor. Small pads of conductive material (overlaid lead pads) are formed on top of the sensor in a multi-step process. First a conductive material is deposited at a shallow angle to maximize the sidewall deposition on the photoresist, then ion-milling at a high angle is used to remove the conductive material from the field while leaving the sidewall material. An insulation layer is deposited on the lead material at a high angle, then milled at a shallow angle to remove insulation from the sidewall and leave it on field surfaces. A layer of conductive material is then deposited in electrical contact with the overlaid lead pads. The photoresist pad is stripped leaving the lead pads and the conductive lead material in place. If the sensor includes the ruthenium cap, it is preferably removed at this point with care being taken not to remove excessive amounts material which would damage the sensor. The prior art process can be resumed at this point to add additional lead layers which are formed in contact with the lead pads to extend the lead structure to the outside of the slider to provide the electrical contacts for the sensor.
A first embodiment of the invention is a read head with overlaid leads that only contact the top of the sensor along a confined area.
After a CMP, the hardbias structures 44 as shown in
The photoresist pad 46 is patterned over the approximate center of the sensor to define the active region of the sensor that will lie substantially symmetrical between the leads as shown in
A conductive material 48 is deposited at a shallow angle to maximize the sidewall deposition on the photoresist. Then ion-milling at a high angle is used to remove the conductive material from the field while leaving only the sidewall material as shown in
An insulation layer 51 is deposited on the lead material at a high angle and is then milled at a shallow angle to remove the insulation on side of the lead pads as shown in
The photoresist is stripped off leaving the lead overlay pads 48A, 48B with the connecting lead material 53 exposed as shown in
The remainder of the lead structure can be completed according to the prior art which typically builds additional layers of conductive material to shape and direct the leads to the outside of the sensor.
The invention has been described with respect to particular embodiments, but other uses and applications for the thin film structures according to the invention will be apparent to those skilled in the art.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US7194797 *||Jun 30, 2004||Mar 27, 2007||Hitachi Global Storage Technologies Netherlands B.V.||Method for use in forming a read sensor for a magnetic head|
|US20030011943||Jul 12, 2001||Jan 16, 2003||Webb Patrick Rush||Overlaid lead giant magnetoresistive head with side reading reduction|
|US20030182790 *||Mar 28, 2002||Oct 2, 2003||Richard Hsiao||Methods of making magnetic heads with improved contiguous junctions|
|US20040061987 *||Sep 27, 2002||Apr 1, 2004||International Business Machines Corporation||Self-stabilized giant magnetoresistive spin valve read sensor|
|US20040257713||Jun 17, 2003||Dec 23, 2004||Pinarbasi Mustafa Michael||Lead overlay magnetoresistive sensor|
|US20050007706||Aug 10, 2004||Jan 13, 2005||Headway Technologies, Inc.||Lead overlay bottom spin valve with improved side reading|
|US20050135019||Feb 7, 2005||Jun 23, 2005||Hitachi Global Storage Technologies Netherlands B.V.||Thin film head reader with lead overlay a method of fabrication thereof|
|U.S. Classification||29/603.16, 216/65, 360/327, 451/41, 29/603.15, 360/324.12, 360/324.2, 29/603.13, 360/324.11, 29/603.14, 360/325, 451/5, 216/62, 29/603.18, 216/66|
|International Classification||H04R31/00, G11B5/127|
|Cooperative Classification||G11B5/3929, Y10T29/49043, Y10T29/49052, Y10T29/49048, G11B5/3932, Y10T29/49032, Y10T29/49044, Y10T29/49046, G11B5/398|
|European Classification||G11B5/39C5, G11B5/39C1H2, G11B5/39C1H|
|Sep 12, 2005||AS||Assignment|
Owner name: HITACHI GLOBAL STORAGE TECHNOLOGIES NETHERLANDS B.
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHEN, TSUNG YUAN;DILL, FREDERICK HAYES;FREITAG, JAMES MAC;AND OTHERS;REEL/FRAME:016770/0167;SIGNING DATES FROM 20050804 TO 20050816
|Aug 29, 2012||FPAY||Fee payment|
Year of fee payment: 4
|Oct 25, 2012||AS||Assignment|
Owner name: HGST, NETHERLANDS B.V., NETHERLANDS
Free format text: CHANGE OF NAME;ASSIGNOR:HGST, NETHERLANDS B.V.;REEL/FRAME:029341/0777
Effective date: 20120723
Owner name: HGST NETHERLANDS B.V., NETHERLANDS
Free format text: CHANGE OF NAME;ASSIGNOR:HITACHI GLOBAL STORAGE TECHNOLOGIES NETHERLANDS B.V.;REEL/FRAME:029341/0777
Effective date: 20120723
|Oct 14, 2016||REMI||Maintenance fee reminder mailed|